DESCRIPTION (provided by candidate): The basic science of Wnt signaling in normal and abnormal pituitary gland function is an area of exciting endocrinology research. The goal of this research proposal is to characterize the effects of Wnt-10A on thyrotrope cells. Utilizing the murine TtT-97 thyrotropic tumor model of hyperplasia, I previously demonstrated that treatment of TtT-97 tumors with thyroid hormone reduced tumor size in association with decreased expression of the Wnt-10A ligand. The purpose of this grant proposal is to elucidate the role of Wnt-10A in thyrotropes, specifically: 1) to characterize the effects of Wnt-10A on Wnt signaling, cellcycle genes, and growth in thyrotrope cells, 2) to identify the cis-acting promoter elements that regulate Wnt-10A expression in TtT-97 cells, 3) to establish the pituitary localization and thyroid hormone responsiveness of Wnt-10A expression, in vivo, and 4) to elucidate the effects of Wnt-10A over-expression on thyrotrope cells. To better characterize factors that regulated Wnt-10A gene expression, model systems of regulated (TtT-97) and unregulated (alpha-TSH) thyrotrope cell growth will be compared. In order to achieve these scientific objectives, research methods that utilize Wnt-10A loss-of-function and over-expression will be performed. Specifically, siRNA technology will be utilized to study the effects of Wnt-10A knock-down on cell-cycle genes and growth in TtT-97 and alpha-TSH cells. Next, Wnt-10A over- expression studies will then be performed to characterize the Wnt signaling pathway and cell-cycle genes that are activated by Wnt-10A and further define important regulatory elements. Further studies are then proposed to define the cis-acting elements of the Wnt-10A promoter that regulate basal activity and thyroid-hormone responsiveness. To establish the thyrotrope localization of Wnt-10A and its thyroid hormone responsiveness in the murine pituitary gland, in situ hybridization studies are then proposed. Lastly, to determine the in vivo effects of Wnt-10A over-expression on thyrotrope cells, a transgenic mouse model is proposed. The primary goal of this basic research study is to advance the understanding of thyrotrope cell physiology. The principle investigator, Janice Kerr, is a physician, post-doctoral fellow with a strong commitment to basic science research and a career in academic medicine. The short-term goals of the principle investigator are to advance her research skills in the area of molecular biology and Wnt signaling. Her long-term goals are to become a well-trained, independent-scientist in the field of endocrinology. The research proposed is relevant to public health in that Wnt signaling is a well-recognized factor in normal development and human malignancies, and further understanding of Wnt-10A may elucidate its role in normal and abnormal pituitary processes.